2005 was devastating for coral with unusually warm waters in the tropical Atlantic Ocean and Caribbean Sea causing one of the worst bleaching events on record, however, researchers who monitored that event warn that 2010 could be even worse.
Mark Eakin, coordinator of the US National Oceanic and Atmospheric Administration’s Coral Reef Watch, and his colleagues performed an extensive coral survey to record the effects of unseasonally high temperatures on reefs in 2005. The project involved more than 250 collaborators from 22 countries and compared satellite data with field surveys to determine how heat stress affected the coral in different places.
In a paper published in PLoS ONE, the researchers reported the most severe coral bleaching ever recorded in the Caribbean: more than 80% of the corals surveyed were bleached and at many sites more than 40% died. Mark Eakin said, “Severe, widespread bleaching spells trouble for tropical marine ecosystems in general.”
The researchers also saw bleaching in places where it had not been recorded before, for example at the Flower Garden Banks National Marine Sanctuary in the Gulf of Mexico. They also saw the first mass bleaching of elkhorn coral in the Virgin Islands National Park.
Several factors can cause bleaching but, according to Mark Eakin, the only thing that could cause mass bleaching on this scale is high temperatures maintained over a period of months.
Mark Eakin is concerned that 2010 has been devastating for coral as, for only the second time (the first being in 1998), bleaching has been observed in every ocean and major sea in which coral occurs: “We’re looking at an event of the same magnitude, with temperatures on a par with what we saw in 2005. As far as corals are concerned, 2010 is, in places, as bad as or worse than 2005.”
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